The present invention generally relates to medical catheters for delivery of medicaments directly to treatment sites within a living body. More particularly, the invention relates to infusion catheters having electro-osmotic features which incorporate electrical charges and voltage drops to facilitate the localized medicament delivery. The electrodes across which the voltage drop is experienced are components of the catheter itself, and any need for external electrodes is eliminated.
Medicaments can be administered to living bodies by a number of approaches, including topical administration, intravenous administration, injection into body tissue via hypodermic needles and the like, and oral administration. In some instances, it is important to minimize the contact of the medicament with areas of the body other than the specific area targeted for treatment. For example, such an approach reduces the dilution effect by having to distribute the medicament to portions of the body that do not require the treatment. Direct delivery to the target site also minimizes the chance of side effects by restricting the drug administration to the precise site in need of treatment. In other instances, the area to be treated is not readily accessible in the absence of fully invasive surgery, such as when it is desired to treat the interior of a blood vessel or other body vessel or cavity.
Over the years, infusion catheter systems have been developed in order to deliver medication, pharmaceuticals, drugs or other medicaments to a localized site by the use of injection from a distal portion of a catheter such as an intravenous catheter or the like. One difficulty that has been encountered in connection with infusion catheter systems is the development of streaming. In many infusion catheter systems, a liquid medicament is injected under pressure, such as by way of a hypodermic syringe or a pumping device, from out of a distal end portion of an intravascular catheter. Often, this entails injection pressures which can be relatively high when compared with a possibly delicate condition of a diseased or damaged vessel or the like such that there is a concern that vessel trauma can occur by high pressure streaming, particularly when the exit port is directed toward the vessel wall or the like. Accordingly, such approaches have the possible disadvantage of being somewhat mechanically traumatic. Also, such direct injection approaches can be less controlled, especially in the sense of delivering medication over a preselected period of time.
Approaches have been taken or proposed in order to improve these types of mechanical infusion catheter systems. Included in this regard are systems which are designed to selectively and locally deliver a drug or medicament to internal body tissue, which systems include a perforated, permeable or semi-permeable material through which the drug or medicament selectively passes. Exemplary in this regard is Shapland et al PCT International Publication No. WO 91/19529, incorporated by reference hereinto. This publication also generally mentions that passage through such a membrane can be facilitated by utilizing so-called iontophoresis technology for this type of transdermal medicament delivery. Iontophoresis technology uses an electrical potential or current across a semi-permeable barrier to drive ionic medicaments toward the target treatment site. Iontophoresis can also include the concept of dragging non-ionic medicaments across the semi-permeable barrier by incorporating same within an ionic solution or carrier. At times, particularly when water is the carrier, this latter approach can be referred to as iontohydrokinesis.
Another approach in this regard is found in Feiring U.S. Pat. No. 5,236,413, incorporated by reference hereinto. Both this patent and the Shapland et al PCT publication propose using iontophoresis or iontohydrokinesis as described in these references by the use of an electrode which is external to the patient's body. By this latter approach, an internal electrode is positioned inside of a permeable balloon. An electric field is developed between this internal electrode and an external electrode or electrodes such as patch or paddle electrodes that are positioned on the outside surface of the body. In accordance with this approach, medication is delivered into the balloon and weeps through the minute pores of the balloon during generation of the electric field between the internal electrode and the external or return electrode.
In accordance with the present invention, the undesirable aspects of having to pass the electrical current through body tissue because of the potential set up between an internal electrode and an external return electrode are eliminated. Instead, an internal electrode is combined with another electrode which is positioned on the catheter itself, which is considered to be integral with respect to the catheter. By this approach, any external catheter is eliminated. The physician need only insert the electro-osmotic infusion catheter in accordance with customary catheter insertion techniques. The self-contained approach of the present invention is easier to use and less complicated for the physician. The step of having to properly place the external return electrode is completely eliminated. Also eliminated is the possibility of creating stray electric fields within the body, inasmuch as the electric circuit is confined to a specific area at the distal portion of the catheter itself and typically within the vessel itself. The medicament distribution is more uniform, and the medicament delivery itself is more efficient by proceeding in accordance with the present invention.
In summary, the present invention is an electroosmotic infusion catheter and procedure for delivery of medicaments or treatment fluids to a location within a living body. The catheter carries out localized treatment of internal body tissue, such as re-stenosis reduction and the treatment of cancers by localized delivery of drugs to a tumor location, for example. The distal portion of the catheter includes one or more balloon components to define a treatment location and/or to treat diseased or injured areas. Delivery is facilitated by the use of an electrical circuit which includes an internal electrode and an integral electrode that is positioned along the catheter at its distal portion, which electrical circuit influences the path of travel of the medicament to direct same toward the area being treated.
It is a general object of the present invention to provide an improved infusion catheter and method of using same.
Another object of the present invention is to provide an improved infusion catheter that carries out localized treatment of internal body tissues.
Another object of this invention is to provide an improved infusion catheter which uses an integral electrical circuit confined to the distal end portion of the infusion catheter.
Another object of the present invention is to provide an improved infusion catheter and procedure using electro-osmotic principles to deliver medicaments to locations within a living body that are accessible through catheterization procedures.
Another object of the present invention is to provide an improved catheterization procedure which effects electro-osmotic infusion of medicaments to localized sites within a living body in accordance with a self-contained approach which avoids the need for an external electrode.
Another object of this invention is to provide an improved infusion catheter and medicament infusion procedure by a self-contained electrical circuit approach which is of enhanced efficiency and uniformity with respect to medicament delivery.
Another object of this invention is to provide an improved infusion catheter and medicament infusion procedure which avoid the creation of stray electric fields within the body.
Another object of the present invention is to provide an improved infusion procedure and catheter which reduces restenosis development after an angioplasty procedure by directing treatment fluid to a localized area at the site of an angioplasty treatment.
Another object of this invention is to provide an improved infusion procedure and catheter for localized treatment of cancers.
Another object of this invention is to provide an improved infusion catheter and treatment procedure wherein catheter balloons generally flank a treatment area at which medicaments under the influence of an integral voltage drop are directed to that treatment location.
Another object of the present invention is to provide an improved infusion catheter and procedure which virtually eliminate potentially disruptive or damaging streaming of medicament flow onto the treatment site.
These and other objects, features and advantages of the present invention will be clearly understood through a consideration of the following detailed description.